When I fitted these years ago the way I did it was bolt it all together looseley ,the TCA end with the hole in will only really be an easy fit at one point , as soon as you fit the first one it will be clear where that point is . You also have to find the "sweet spot " where as the suspension is in full droop the twisting action of the bottom arm will turn the compression strut and then adjust the spherical joint so it is just clearing the top hat bushes at the chassis mount , it does not take long , just a little bit of patience , then you have to set the castor and repeat the process untill the caster is set and the joint is still clear , there is several ways you can short cut the process to set the castor to a "ballpark" setting , like locking the wheels in the straight ahead position lifting car up on 4 axle stand , remove caliper and use the caliper bolt holes as your datum , take a reading of this and once you have put the compression struts on adjust until this datum figure is reached , I always balance the 2 sides so at least they are the same .

Hope my rambling made sense .